Waterproof housings are known in the prior art for containing rechargeable, battery-operated power supplies for use in various applications. When the batteries of such power supplies are being charged, and resultant electrochemical action produces gaseous by-products which build up within the enclosure and must be permitted to escape therefrom. Prior art enclosure or housing designs have thus incorporated gas escape vents which may alternately be capped to provide a watertight seal when the equipment is in use and easily opened during the charging operation. If the user forgets to reseal one or more of these vents upon conclusion of the charging operation, the housing is, obviously, not watertight. If it is not realized that this situation exists, the equipment may be used as though it were watertight, permitting water to enter the housing and damage the batteries and charging apparatus therein contained. Further, should the equipment have dropped into a body of water, the open vent may lead to sinking of the unit, rather than the expected floating thereof.